Crystalline linagliptin intermediate and process for preparation of linagliptin

Abstract

The present invention provides novel crystalline forms B1 & B2 of linagliptin intermediate of structural formula V and methods for production of novel crystalline form of linagliptin intermediate represented by the following structural formula V.

The invention claimed is: 
     
       1. A crystalline form B1 of Linagliptin intermediate of formula V, 
       
         
           
           
               
               
           
         
         characterised by an XPRD pattern in accordance with  FIG. 1 . 
       
     
     
       2. The crystalline form B1 of Linagliptin intermediate of formula V, of  claim 1  having prominent peaks at 3.14±0.2, 6.31±0.2, 8.34±0.2, 10.93±0.2, 13.75±0.2 & 14.46±0.2 degrees 2θ. 
     
     
       3. The crystalline form B1 of Linagliptin intermediate of formula V, of  claim 1  having DSC endotherms at 53.87 & 162.97° C. 
     
     
       4. The process for preparation of crystalline form B1 of Linagliptin intermediate of formula V, of  claim 1  comprising following steps of:
 a. Heating crude linagliptin intermediate of formula V in a solvent, 
 b. Adding a suitable anti-solvent to the reaction mass of above step at elevated temperature, 
 c. Heating the reaction mass to an elevated temperature, 
 d. Reaction mass was cooled and isolated the crystalline form of Linagliptin intermediate of formula V. 
 
     
     
       5. The process for preparation of  claim 4 , wherein solvent is acetonitrile. 
     
     
       6. The process for preparation of  claim 4 , wherein anti-solvent is water. 
     
     
       7. A crystalline form B2 of Linagliptin intermediate of formula V, 
       
         
           
           
               
               
           
         
         characterised by an XPRD pattern in accordance with  FIG. 4 . 
       
     
     
       8. The crystalline form B2 of Linagliptin intermediate of formula V, of  claim 7  having prominent peaks at 3.43±0.2, 8.10±0.2, 9.96±0.2 & 17.02±0.2 degrees 2θ. 
     
     
       9. The crystalline form B2 of Linagliptin intermediate of formula V, of  claim 7  having a DSC endotherm at 168.69° C. 
     
     
       10. The process for preparation of crystalline form B2 of Linagliptin intermediate of formula V, of  claim 7  comprising following steps of:
 a. Treating crude linagliptin intermediate of formula V with preheated solvent, 
 b. Adding an anti-solvent to the reaction mass of above step, 
 c. Heating the reaction mass to an elevated temperature, 
 d. Reaction mass was cooled and isolated the crystalline form of Linagliptin intermediate of formula V.